My understanding is that docker needs App Engine Flexible Environment.
But I want to use Docker to create dev and local testing environment only, so that it will be easier and faster to replicate the environment on dev machines. I still want to deploy the GoLang app to App Engine Standard Environment. I am wondering if there is a way?
You can build custom runtimes using Docker, you will only need App Engine Flexible if you want to deploy them. In your case, as you want to deploy to App Engine Standard, I would recommend using the Development Server to simulate correctly the environment.
You cannot use Containers with App Engine Standard. You can use containers with App Engine Flexible.